Jun 30, 2007 - It is found in kimchi, silage, cheese, sauerkraut, sour- dough, and smoked fish but is mainly found in meat products. (4, 7, 8). Though some L.
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Mar. 2008, p. 1394–1401 0099-2240/08/$08.00⫹0 doi:10.1128/AEM.01463-07 Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Vol. 74, No. 5
Two Different Tetracycline Resistance Mechanisms, Plasmid-Carried tet(L) and Chromosomally Located Transposon-Associated tet(M), Coexist in Lactobacillus sakei Rits 9䌤 Mohammed Salim Ammor,1§ Miguel Gueimonde,1 Morten Danielsen,2 Monique Zagorec,3 Angela H. A. M. van Hoek,4 Clara G. de los Reyes-Gavila´n,1 Baltasar Mayo,1 and Abelardo Margolles1* Instituto de Productos La ´cteos de Asturias (CSIC), Carretera de Infiesto s/n, 33300 Villaviciosa, Asturias, Spain1; Chr. Hansen A/S, Bøge Alle´ 10-12, 2970 Hørsholm, Denmark2; Unite´ Flore Lactique et Environnement Carne´, UR309, INRA, Domaine de Vilvert, F-78350 Jouy-en-Josas, France3; and RIKILT – Institute of Food Safety, Wageningen UR, Bornsesteeg 45, Wageningen, The Netherlands4 Received 30 June 2007/Accepted 26 December 2007
Lactobacillus sakei is extensively used as functional starter culture in fermented meat products. One of the safety criteria of a starter culture is the absence of potentially transferable antibiotic resistance determinants. However, tetracycline-resistant L. sakei strains have already been observed. In this paper, we show that tetracycline resistance in L. sakei Rits 9, a strain isolated from Italian Sola cheese made from raw milk, is mediated by a transposon-associated tet(M) gene coding for a ribosomal protection protein and a plasmidcarried tet(L) gene coding for a tetracycline efflux pump. pLS55, the 5-kb plasmid carrying the tet(L) gene, is highly similar to the pMA67 plasmid recently described for Paenibacillus larvae, a species pathogenic to honeybees. pLS55 could be transferred by electroporation into the laboratory strain L. sakei 23K. While the L. sakei 23K transformant containing pLS55 displayed an intermediate tetracycline resistance level (MIC,
